船舶动力定位能力分析程序开发研究

本文根据船舶动力定位系统的工作原理,基于MATLAB语言将环境载荷计算、推力计算、推力分配、图形绘制等功能进行集成,完成动力定位能力频域分析模块开发;然后结合Kalman滤波算法采用LQR方法进行反馈控制,完成时域分析模块开发。以某型海洋调查船为算例,首先,利用该程序绘制了动力定位能力曲线,并且与Kongsberg Maritime分析报告对比,结果吻合良好,为推进器的选型与布置提供依据;然后,进行时域模拟给出海洋调查船的位置、姿态的时历曲线和各个推进器的推力响应情况,为实际工程提供指导。     

基于频率特性的传感器动态测量不确定度评估

文章以《测量不确定度表达指南（GUM）》中的B类评定方法为基础,根据传感器的频率特性,以幅频特性计算动态测量的相对误差,评估测量值区间半宽和置信因子,然后进一步结合相频特性,评定传感器动态测量不确定度,从而提出了一种基于传感器频率响应特性的测量不确定度评估的通用方法。最后以一种加速度传感器的振动实验为例,验证了上述方法。     

气动载荷对半潜式海上风机运动响应的影响分析

以DeepCwind海上风机为研究对象,利用有限元软件ANSYS AQWA进行风机频域水动力数值仿真分析,得到水动力参数以及幅频响应曲线,将得到的水动力参数导入到FAST软件中,对风机气动-水动-锚泊系统的时域耦合运动分析。在此基础上,讨论了气动载荷对于半潜式风机运动响应的影响。结果表明,气动载荷对于半潜式风机运动响应的影响较大且不可忽略,横摇,横荡以及首摇运动随着气动载荷的增大而增大,垂荡运动随着气动载荷的增大而减小,风作用在叶片上所产生的气动阻尼削弱了垂荡运动,增强了横荡、横摇和首摇运动。     

基于RFID的器材物资及车辆人员信息化管理系统的研究

利用新一代射频卡作为帐物卡、收发卡、运输卡、登记卡、身份卡等,在器材管理环节中实现不同类型数据更加快速准确地传递、获取和统计。从而达到器材物流无缝链接,显著提高器材保障工作效率与质量的目标。     

典型故障下自耦变压器分裂式绕组的频率响应特征

基于搭建的自耦变压器分裂式绕组故障模拟试验平台,在各独立绕组上模拟短路和轴向移位2种典型故障,测试无故障、典型故障下分裂式绕组的整体频率响应和各独立绕组的频率响应;计算特征频带内故障时相对于无故障时频率响应频率和幅值的偏移量,并模拟分析绕组故障下电气参数,探究频率响应特征及其变化机理.结果 表明:在0～100 kHz低...     

Iterative methodology for response based analysis of an FPSO mooring system

Response based analysis (RBA) has been developed for prediction of extreme N-year return period responses and design metocean conditions of offshore structures. For applying the RBA, the behaviour of the offshore system subjected to a long history of metocean conditions needs to be predicted, and then, the probabilistic analysis is applied to estimate its long-term responses. Due to the large number of analysis cases required, the structural simulation is usually performed either by simplifying the structural model or by using computationally efficient tools, such as frequency-domain (FD) analysis. These approaches usually decrease the accuracy of predictions mainly when they are utilized for nonlinear systems. On the other hand, employing time-domain (TD) simulations leads to more accurate results but it is computationally expensive. Application of RBA for a weathervaning FPSO, which is the subject of the present study, makes TD analysis an essential requirement because of a highly nonlinear behaviour of the system. In the present study, an efficient methodology is proposed that aims at reducing the computational efforts of RBA by joint application of TD and FD simulations in combining the structural and statistical analyses through a single process, such that the number of time-consuming TD simulations is minimized. After initial screening using the results from FD simulations, the methodology identifies the response events (storms) that contribute the most to the N-year response and sets out an iterative process in which only those events that are most important are analysed by fully-coupled TD simulations. Within such events, a similar approach is also applied to intervals (sea states) where only the most contributing intervals are analysed in TD, and the remaining intervals are left for a less accurate FD analysis without sacrificing the overall accuracy. The proposed methodology provides a robust framework for distinguishing between “mild” and “severe” response events, without specifying any predefined limits for the metocean parameters or making a subjective judgement. Although it is developed for the mooring system of a weathervaning FPSO, it should also be applicable to any type of offshore structure and any structural response. This paper is the first part of the study and concentrates on the development of the efficient methodology to optimize the application of RBA to FPSO mooring systems, whilst its detailed application is subject of the second part of the study.     

Fatigue life estimation of explosive cladded transition joints with the use of the spectral method for the case of a random sea state

The problem with fatigue lifetime estimation of explosive cladded transition joints under random loading conditions has been described. The paper presents the fatigue test results performed for the random state of tension-compression under a generated spectrum according to the Pierson-Moskowitz model. The obtained spectrum has a non-Gaussian characteristic. The tested material consists out of a transition joint clad with four layers of aluminium alloy A5083, A1050, Titanium Grade 1 and steel Grade D. The material has been tested for the existence of residual stresses after the welding process with the hole drilling method. The welding process has been also simulated with ANSYS and the residual stresses have been generated for the Goldak volumetric distribution. The obtained values of residual stresses comprise to the values of real tests performed for the hole drilling method. The information about the residual stress values have been taken into account in the process of fatigue lifetime estimation in the form of non-zero mean stresses compensation inside the clad. The fatigue life has been calculated with the use of the frequency domain method. The Goodman mean stress compensation model has been used in the process of residual stress compensation. The non-gaussianity has been compensated with the use of the Bracessi formula. The obtained fatigue life assessment results have been compared with stand test results. The calculated results are within the scatter area of 3, but individual scatter values have been calculated for calculated series.     

Heave-Pitch-Roll Dynamics of Flexible Vehicle in Variable Velocity Run

Analysis for response statistics evaluation of a flexible vehicle travelling with variable velocity over nonhomogeneously profiled flexible track is presented with a heave-pitch-roll model. The vehicle body is idealised as a flexible member with variable cross-section, inertia, damping and stiffness distributions. The vehicle may also have variable section slender elastic attachments. Coupled dynamics with rigid body heave-pitch-roll modes and elastic bending-torsion modes of the vehicle body along with coupled bending-torsion modes of the attachments are considered. Equivalent linear suspension system characteristics are employed for developing the analysis. Numerical results are presented for an aircraft with tricycle landing gear arrangements and comparison is made with other models.     

20.5万吨散货船轴带发电机系统设计研究

为降低大型商业运输船舶无限航区航行时能源消耗,在20.5万吨级大型散货船上采用PWM型轴带发电机,以降低运输成本,提高环保性能,提高经济效益。     

浮式抗冰平台设计理念及水动力特性研究

钻探极地地区近海石油和天然气资源对移动式离岸钻井平台的水动力性能、抗冰性能和作业性能有着极大的要求。本文主要介绍了浮式抗冰平台的设计方案,并结合当今最新一款半潜式抗冰平台的设计理念,分别从频域和时域分析的角度与传统的半潜式平台作对比,分析得出其具有优越的水动力性能,垂荡、横摇、纵摇运动响应都优于传统的半潜平台,为下一步抗冰性能分析及其关键技术的研究做基础,同时也给半潜式平台带来新的设计理念,为浮式抗冰平台的设计建造提供合理思路。